The invention relates to a hand-held device for the transfer of film from a tape applicator onto a substrate.
A hand-held device of this type (alternately referenced herein as a tape applicator for the sake of convenience without any intent to limit) is described in EP 0 507 818 B1 (corresponding U.S. Pat. No. 5,303,759 to Czech). This known hand-held device comprises a housing and an application member which extends from the interior of the housing to the outside through an opening in the housing. The application member has a swivelling axis in the form of a curved bulge which is connected to a plate-shaped application body by a lateral longitudinal web. A spatula, in the form of an extension, extends from the outward-pointing front end of the application body or apparatus. The spatula forms an application end or edge of the application member for a backing tape which extends outwards from a supply reel rotatably mounted in the housing to the ridge of the spatula where it is deflected and then stretches back inwards to a take-up reel rotatably mounted in the housing. In this known design, the spatula is arranged as a front-end extension of the application body such that it is laterally offset from a swivelling axis, namely towards the side with which the hand-held device is to be placed on or applied to a substrate in the operating mode. The swivelling axis is arranged laterally offset on the longitudinal web and is mounted in a correspondingly curved undercut bearing groove of a bearing part in the housing, wherein the gap between the side edges of the bearing groove is greater than the thickness of the longitudinal web. As a result, the thus formed bearing for the application member has a degree of freedom in the peripheral direction which allows a limited lateral to and fro swivelling of the application member relative to the housing and thus adaptation to a laterally inclined substrate surface. This makes it easier to handle the device, wherein the spatula can also adapt to the substrate surface if the substrate is laterally inclined or if the device is applied at a slant.
As a result of the laterally offset arrangement of the spatula in relation to the swivelling axis, however, this known arrangement has a relatively large and bulky construction caused by the offset. This is undesirable in a device of this type because a large construction, especially in the region of the housing opening, particularly obstructs the user""s view of the application member when the application is to be positioned accurately, for example, when applying the coating onto just a certain surface section of the substrate. In addition, the known device has a complicated construction causing complex and costly manufacture and assembly which leads to high production costs. As the device in question is a typical mass-production product, simple design and assembly is desirable in order to reduce production costs.
In the hand-held device known from EP 0 507 818 B1 (corresponding U.S. Pat. No. 5,303,759 to Czech), the application member is mounted so as to be freely pivotable in the restricted swivelling region. As a result of gravity, the application member will therefore always adopt a position in which its application member body supporting the spatula points downwards. This impairs handling because the spatula can be slanted in relation to the hand-held device as a whole. This leads to the spatula being applied to the substrate at a lateral inclination, particularly when the film is applied onto an inclined substrate. Only once the application member is pressed onto the substrate is the application member pushed into its position parallel to the substrate. A further disadvantage of the design according to this patent is that, when the application member bears on its swivel stops, a lateral tilting of the spatula during moving of the device when applying the film can hardly be avoided and this impairs the film application.
The present invention is a device for applying a film to a substrate designed such that the housing can be formed with a small structure in the application member region. A structure which can be manufactured and assembled simply and inexpensively is desired in order to reduce the production costs of the device.
The application end of the application member of a device formed in accordance with the principles of the present invention is formed by an extension of the bearing section, the application end and the bearing section enclosing an obtuse angle therebetween. This makes it possible to achieve a simple and material-saving construction, wherein an additional application body portion laterally offset from the bearing section as present in the generic device can be omitted. Thus, space is created in which the housing can be formed smaller in the region of the opening, leading to a better view which allows accurate working with the hand-held device, for example, for applying the film onto certain areas which can also be relatively small as they are easier to see as a result of the improved view. In doing so, the ergonomic advantage resulting from the application end and its ridge being offset from the swivelling axis of the bearing section is maintained. In an embodiment formed according to the principles of the present invention, this is achieved by the bend or curve. A further advantage of the embodiment according to the principles of the present invention consists in the fact that, owing to the lower material usage, it is also lighter in weight and is therefore advantageous not only from an ergonomic point of view but also for weight-saving reasons.
The embodiment according to the principles of the present invention is particularly suitable for an application member having an application end in the form of a spatula which, as a result of its flat or wedge-shaped advance to a thin ridge, allows its position on the substrate to be accurately visually determined and the film to be accurately applied to the substrate.
In this type of device having an application member, the free application end of which is formed by a spatula, a lateral guide for the film is needed in the spatula region to guarantee that the film does not slip away sideways during its sliding circulation at the ridge of the spatula. In this respect, it is known to arrange side guiding webs or guide wings (alternately referenced herein as guiding webs without any intent to limit) on both broad sides of the spatula between which the film slides during operation.
The invention is based on the knowledge that sufficient guidance is also guaranteed if just one guiding web is arranged on each broad side of the spatula, both of which webs are however arranged on both sides of the film so that the guiding web on one broad side forms a lateral guide and the other guiding web on the other broad side forms a guide on the other side of the film. This not only saves on material, but this design also contributes towards improving the view of the application point so that the film can also be applied accurately to the substrate in this aspect of the invention. The spatula with its guiding webs can be formed with a Z-shaped cross-section. In this case, the guiding webs are located in a common transverse plane.
The construction of the device formed in accordance with the principles of the present invention is simple and inexpensive to produce and improves pivoting guidance and axial positioning.
The present invention also provides a device that facilitates application of a film to a substrate.
To achieve this object, the swivel movement stops for the application member are formed in a resiliently flexible manner. As a result, the application member can still adapt to positioning differences between the device and the substrate, also within the region of its lateral restriction, and so a full or linear application is still guaranteed. To achieve this, the swivel movement stops can be formed by spring elements which guarantee the elasticity in the side pivot end region. It is particularly advantageous when the application member is mid-centered in a central swivel position by elastic forces. In such an embodiment, the application member is always located in a position defined with regard to the device although the lateral freedom of motion is guaranteed and the application member can adapt laterally in this region.
Another particularly simple design is produced when one single spring guarantees the mid-centering, wherein the spring can be arranged on the application member with its free end section positioned on the housing or can be arranged on the housing with its free end positioned on the application member. Within the scope of the invention, this spring can be a spiral spring or a torsion spring.